An automation technology for excavating and loading has been adopted to such an artificial system environment as an asphalt plant. In this system, guide path wires are underlaid between a material storage yard to a hopper, and the materials in the material storage yard are loaded onto the hopper by moving such an automatic excavating machines as a power shovel and a wheel loader along these guide path wires.
The guiding system using guide path wires laid like this, however, is only suitable for a stationary type system in which a material storage yard, a hopper, etc. are installed at fixed positions, but cannot be used for a site where the working position constantly changes, such as a civil engineering work site which includes a rock crushing site, mine and land development. In such a civil engineering work site, loading objects are normally not a stationary type, such as a hopper, but are a mobile type, such as a dump truck, and in this case, because the dump truck does not always remain in the same position, a function to automatically recognize the position of the dump truck is necessary.
A conventional automatic excavating and loading technology which has been applied to a civil engineering work site in a natural environment, including an excavating site, mine and land development, is disclosed in Japanese Patent Laid Open No. 5-297942.
In this conventional art, a current position of a crawler dump truck is computed in real-time, by a bi-directional tracking system comprising an automatic tracking unit disposed at the crawler dump truck and an automatic tracking unit disposed at a fixed station, and by a coordinate position computing system disposed at the crawler dump truck. The crawler dump truck automatically travels along the traveling path while comparing this computed current position with the traveling path coordinates which are set such that the loading position (excavating position) and the unloading position are connected. At the loading position (excavating position) where earth is loaded using a power shovel, the shape of excavation object for loading is measured by an ultrasonic sensor installed on the power shovel, and the working pattern of the power shovel is determined based on this, so that the excavation object is automatically loaded onto the crawler dump truck without any human operators.
In this conventional art, where the shape of excavation object is recognized by an ultrasonic sensor, the shape of excavation object, which is the object of excavation, cannot be accurately measured since the ultrasonic sensor can only measure a distance to one point. Also, an ultrasonic sensor, which can measure only a short distance, cannot be used for an excavation and loading operation where the moving range is large.
Also in this conventional art, a position of the mobile type loading object (in this case, a crawler dump truck) and a relative attitude of the excavator (in this case, a power shovel) with respect to the loading object, are not detected. Therefore, the position of the loading object and the relative attitude of the excavator with respect to the loading object cannot always be detected accurately at the excavator side. As a result, excavation object is frequently spilled, and in an extreme case, collision between the excavator and the loading object may occur.
With the foregoing in view, it is an object of the present invention to provide an automatic excavator which can carry out a series of operations, from excavation to loading, automatically and efficiently using one automatic machine.
It is another object of the present invention to provide an automatic excavator which can carry out an efficient excavation operation by increasing the amount of excavation object to be excavated at each excavation.